feat: add Swagger UI docs, custom CORS middleware, and request logging

- Add Swagger UI files and updated API spec for Family Safety Tracker
- Replace shelf_cors_headers with custom CORS middleware in server.dart
- Add request_logger middleware with timing for auth and geo routes
- Add REGISTRATION_SECRET_KEY to .env for registration validation
- Remove postgres port exposure from docker-compose.yml
- Update opencode.json model configuration
- Add crypto dependency and update Flutter web assets

pubspec.yaml

@@ -16,6 +16,7 @@ dependencies:
   uuid: ^4.5.0
   shelf_cors_headers: ^0.1.5
   shelf_static: ^1.1.3
+  crypto: ^3.0.3
 
 dev_dependencies:
   http: ^1.2.2